In some situations, it is necessary to provide a regulated d.c. potential, and many useful circuits have been developed for this purpose. Known voltage regulators are subject to possible malfunction. The present invention does not pertain to voltage regulators, but rather to a circuit for monitoring a potential, which may or may not be regulated, and providing a signal if the potential should rise above, or fall below, critical levels. Detection of a potential excursion outside the allowed limits may be required to prevent the possibility of the connected load producing a false output as a consequence of the improper potential. Prior art monitoring circuits were deficient in that failure of the monitor circuit itself did not result in a fail signal.
The present invention could find utility in a wide range of applications. It was conceived for use with a railroad signalling application wherein an improper d.c. voltage level could result in the production of an improper signal. The present circuit detects the improper voltage excursion and produces an appropriate signal. The monitor may also be used in connection with industrial processes wherein voltage levels are critical, or in various sensing devices wherein the sensing is inaccurate if the applied potential is outside a specified range, or in computer systems which have critical voltage requirements. Many other applications will readily occur to those familiar with the arts requiring a fixed level d.c. potential.